World ethanol production is expected to experience double-digit growth in the next years. Much of the growth is expected to occur in the United States where, with the current pace of expansion, the United States will be the leading producer of ethanol in the near future.
In the United States, ethanol is made almost exclusively from corn. As of December 2006, 16% of the United States corn crop was being used to displace 3% of the nation's annual gasoline consumption. The US government has a stated goal of reducing its dependence on foreign oil by 20%. If this reduction were to come entirely from corn based ethanol it would use up the nation's corn crop. As a result there has been a considerable amount of research in the production of ethanol from other sources.
Government and private sector scientists have been working on ways to produce ethanol from cellulosic material. Ethanol produced from switch grass, mixed prairie grasses and woody plants grown on marginal land could potentially meet the growing demand for green fuel. One leading company has targeted the collection of corn cobs, which is currently a waste material, as a cellulosic ethanol feed stock.
Current methods to collect whole cobs are very crude. A small number of farmers have built equipment to be mounted or pulled behind their combines for collecting the cobs separated from the grain. Work is being done to improve the construction of such towed collection devices so that this may become a viable technique.
Research in the feed value available from the entire corn field has determined that high moisture ear corn is equal to or better feed than corn grain for growing feeder cattle or dairy cows. This finding has the advantage of allowing a farmer to recover a higher tonnage of feed per acre than previously thought available. These farmers want to feed a mixture of corn grain and corn cobs to the cattle and now cellulosic ethanol companies are looking at this method of harvesting cobs with interest. Modification of existing corn grain combines is therefore desirable for collection of cobs.
A small number of innovators have experimented with what is known as Corn Cob Mix (CCM) technology. There are not any commercially available systems at this time, however a number of patents listed below teach how to adjust the threshing system of the combine to break the cobs into small sections. A number of different arrangements are then provided for modifying the separating system to collect a mixture of corn cobs and grain in the grain tank of the combine. In all cases the upper sieve is replaced with a CCM sieve and the lower sieve is removed allowing the cobs and grain to be collected below the sieve and transported to the grain tank.
Collection and storage of the mixture of grain and cobs using the CCM system is generally not an issue for a cattle feedlot or dairy operation, as these farmers generally have acquired the necessary equipment to store the feed. However the average corn grain farmer does not have this equipment.
Ethanol companies are looking at field side storage of cobs. These cobs may need to be stored in piles for up to 1 year before being used. The adaptation of the corn cob mix for ethanol use has a number of uncertainties and problems including storage of broken cobs which can lead to spoilage and increased field traffic. In most cases the volume yield of cobs is almost equal to that of the grain. This means that CCM equipped combines will be unloading twice as much as a corn grain harvester, leading to more operator stress, more trips by the grain cart to the combine and back to the pile and this can cause reduced future yields due to soil compaction.
The corn grain farmer will still require his corn separated from the cobs to properly store the grain and give him the marketing freedom of the higher valued corn. Field side separation of the corn from the cobs will be required. There are now 1800 bushel grain carts that can unload in less than 3 minutes commercially available, therefore a large surge tank will be required to handle a quick unload from a large grain cart. The field side separator will need to be very large, will be costly and difficult to move.
The following prior patents are concerned with this general field:
U.S. Pat. No. 6,358,141 (Stukenholtz) issued Mar. 19th, 2002 discloses a combine collection system with at least two on-board bins and appropriate separation equipment to place corn grain in one tank and whole cobs in the second tank. An air supplied separating system is attached to the rear of the combine and the cobs are delivered via air pressure to the second tank placed on top of the combine.
This arrangement has not been and will not be widely commercially available due to the number of different combines in use today. Market acceptance of mounting a tank on top of the combine will be low and there will be issues with transportation and storage of the device.
U.S. Pat. No. 5,256,106 issued Oct. 26, 1993 and U.S. Pat. No. 4,892,505 issued Jan. 9, 1989 both of Shrawder each disclose a combine which is adjusted in the threshing system to reduce cobs to usable segments which are 1 to 3 inches long by adjusting threshing clearances. The material is fed to the cleaning shoe where grain is separated through the upper sieve and the cobs are rejected at the rear end of the upper sieve. An auger is added behind the upper sieve of the cleaning shoe for transportation of the separated cobs to a blower. A second auger is mounted parallel to the first behind the first to collect any missed cobs along with stems for further cleaning. Many single auger residue collection systems of this general type have been sold over the last years. The system, using one or two such augers, is however a very crude method of saving the cobs separated from the grain. There is very little adjustment for changing conditions.
U.S. Pat. No. 4,600,019 (McBroom) issued Jul. 15, 1986 and U.S. Pat. No. 4,548,213 (Phillips) issued Oct. 22, 1985 both disclose a combine which is adjusted to break all cobs into 1 to 3.5 inch pieces. An upper sieve is provided to allow the passage of grain and cobs through while discharging the remaining lighter material and plant debris over its end in a conventional manner. The lower sieve is removed and a mix of grain and cobs is stored in the combine's grain tank.
U.S. Pat. No. 4,466,447 (Hoefer) issued Aug. 21, 1984 discloses a combine which is designed with the tailings to be returned to the threshing section of the combine or at the operator's option to the cleaning section without passing through the threshing section.
U.S. Pat. No. 4,188,160 (Corbet) issued Feb. 12, 1980 discloses a residue saver in the form of an auger and trough which is shown mounted behind the combine's sieve. The residue saver can be adjusted by opening or closing a lower part of the trough to save all materials or only large residue such as cobs. The saved residue is blown into a trailing wagon. This arrangement provides very little adjustment in that simply a hole is cut in the bottom of an auger trough near a fan and the heavy particles drop out and lights get sucked into the fan. This is not near enough control over the cleanliness of the corn cob sample.
U.S. Pat. No. 3,680,291 (Soteropulos) issued Aug. 1, 1972 discloses a specialized corn harvesting machine which harvests and chops up both the corn and the stover. The grain can be stored in a tank, and the stover is stored in the same of in a second tank or spread back on the ground